Inferring transmission routes for foot-and-mouth disease virus within a cattle herd using approximate Bayesian computation

To control an outbreak of an infectious disease it is essential to understand the different routes of transmission and how they contribute to the overall spread of the pathogen. With this information, policy makers can choose the most efficient methods of detection and control during an outbreak. Here we assess the contributions of direct contact and environmental contamination to the transmission of foot-and-mouth disease virus (FMDV) in a cattle herd using an individual-based model that includes both routes. Model parameters are inferred using approximate Bayesian computation with sequential Monte Carlo sampling (ABC-SMC) applied to data from transmission experiments and the 2007 epidemic in Great Britain. This demonstrates that the parameters derived from transmission experiments are applicable to outbreaks in the field, at least for closely related strains. Under the assumptions made in the model we show that environmental transmission likely contributes a majority of infections within a herd during an outbreak, although there is a lot of variation between simulated outbreaks. The accumulation of environmental contamination not only causes infections within a farm, but also has the potential to spread between farms via fomites. We also demonstrate the importance and effectiveness of rapid detection of infected farms in reducing transmission between farms, whether via direct contact or the environment.

A review on detection of SARS-CoV-2 RNA in wastewater in light of the current knowledge of treatment process for removal of viral fragments

The entire globe is affected by the novel disease of coronavirus 2019 (COVID-19 or 2019-nCoV), which is formally recognised as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The World Health Organisation (WHO) announced this disease as a global pandemic. The presence of SARS-CoV-2 RNA in unprocessed wastewater has become a cause of worry due to these emerging pathogens in the process of wastewater treatment, as reported in the present study. This analysis intends to interpret the fate, environmental factors and route of transmission of SARS-CoV-2, along with its eradication by treating the wastewater for controlling and preventing its further spread. Different recovery estimations of the virus have been depicted by the detection of SARS-CoV-2 RNA in wastewater through the viral concentration techniques. Most frequently used viral concentration techniques include polyethylene glycol (PEG) precipitation, ultrafiltration, electronegative membrane, and ultracentrifugation, after which the detection and quantification of SARS-CoV-2 RNA are done in wastewater samples through quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The wastewater treatment plant (WWTP) holds the key responsibility of eliminating pathogens prior to the discharge of wastewater into surface water bodies. The removal of SARS-CoV-2 RNA at the treatment stage is dependent on the operations of wastewater treatment systems during the outbreak of the virus; particularly, in the urban and extensively populated regions. Efficient primary, secondary and tertiary methods of wastewater treatment and disinfection can reduce or inactivate SARS-CoV-2 RNA before being drained out. Nonetheless, further studies regarding COVID-19-related disinfectants, environment conditions and viral concentrations in each treatment procedure, implications on the environment and regular monitoring of transmission need to be done urgently. Hence, monitoring the SARS-CoV-2 RNA in samples of wastewater under the procedure of wastewater-based epidemiology (WBE) supplement the real-time data pertaining to the investigation of the COVID-19 pandemic in the community, regional and national levels.

A critical assessment of the potential vertical transmission hypotheses: Implications for research on the early-life infection with COVID-19

The risk of potential vertical transmission in SARS-CoV-2 infected pregnant women is currently a topic of debate. To explore the correlation between the two, we searched PubMed, Embase®, and Web of Science for studies on vertical transmission of COVID-19. The quality of the studies was evaluated by the Cochrane risk of bias tool. Detailed information of each included case including methods of delivery, protection measures for mothers and neonates at birth, types of specimens, inspection time, results of testing and feeding patterns was collected to assess the possibility of vertical transmission. The results showed that of the 390 neonates reported in 36 studies, 23 were infected with SARS-CoV-2 by potential vertical transmission. From the perspective of virology and pathology, vertical transmission of SARS-CoV-2 was possible via uterus or breastmilk. Some reported potential vertically transmitted neonates could be attributed to horizontal transmission. It is extremely vital to fully elucidate the potential routes of transmission of SARS-CoV-2, implicating clinical practice and nursing to reduce the risk of not only horizontal transmission but also vertical transmission, thus protecting neonates from COVID-19 infection.

Estimation of the SARS-CoV-2 transmission probability in confined traffic space and evaluation of the mitigation strategies

Public transport is a fundamental service for the resumption of work and production, but the enclosed environment and dense population create very favorable conditions for the spread of epidemic infections. Thus, effective public health interventions are urgently introduced. The objective of this paper is to quantitatively estimate the SARS-CoV-2 transmission probability and evaluate the influence of environmental parameters and individual intervention on the epidemic prevention. For this purpose, (1) we estimate the virus emission rate with Diamond Princess Cruise Ship infection data by Monte Carlo simulation and the improved Wells-Riley model, and (2) employ the reproductive number R to quantify diverse mitigation strategies. Different determinants are examined such as the duration of exposure, the number of passengers combined with individual interventions such as mask type and mask-wearing rate. The results show that the SARS-CoV-2 quantum generation rate is 185.63. The R shows a stronger positive correlation with the exposure time comparing to the number of passengers. In this light, reducing the frequency of long-distance journeys on crowded public transportation may be required to reduce the spread of the virus during the pandemic. N95 mask and surgical mask can reduce the transmission risk by 97 and 84%, respectively, and even homemade mask can reduce the risk by 67%, which indicates that it is necessary to advocate wearing masks on public transportation.

Small quantities of respiratory syncytial virus RNA only in large droplets around infants hospitalized with acute respiratory infections

Background

Respiratory syncytial virus (RSV) is a major cause of respiratory tract infections in young children. The predominant transmission routes for RSV are still a matter of debate. Specifically, it remains unclear if RSV can be transmitted through the air and what the correlation is between the amount of RSV in nasopharynx samples and in the air.

Methods

The amount of RSV in the air around hospitalized RSV infected infants in single-patient rooms was quantified using a six-stage Andersen cascade impactor that collects and fractionates aerosols and droplets according to size. RSV shedding in the nasopharynx of patients was followed longitudinally by quantifying RSV RNA levels and infectious virus in nasopharyngeal aspirates. Nose and throat swabs of parents and swabs of the patient’s bedrail and a datalogger were also collected.

Results

Patients remained RSV positive during the air sampling period and infectious virus was isolated up to 9 days post onset of symptoms. In three out of six patients, low levels of RSV RNA, but no infectious virus, were recovered from impactor collection plates that capture large droplets > 7 μm. For four of these patients, one or both parents were also positive for RSV. All surface swabs were RSV-negative.

Conclusions

Despite the prolonged detection of infectious RSV in the nasopharynx of patients, only small amounts of RSV RNA were collected from the air around three out of six patients, which were primarily contained in large droplets which do not remain suspended in the air for long periods of time.

A mixed-methods approach to elucidate SARS-CoV-2 transmission routes and clustering in outbreaks in native workers and labour migrants in the fruit and vegetable packaging industry in South Holland, the Netherlands, May to July 2020

OBJECTIVES

To obtain insight into SARS-CoV-2 clustering and transmission routes during outbreaks in the predominantly migrant workforce of the fruit and vegetable packaging industry of South Holland, the Netherlands, May to July 2020.

DESIGN

This mixed-methods study applied direct observation and interviews, epidemiologic investigation, source and contact data analysis and whole-genome sequencing.

RESULTS

We detected 46 SARS-CoV-2 cases and 4 outbreaks with a proportional representation of labour migrant and native workers in 6 unrelated facilities. Complete viral genome sequences revealed at least 3 clusters of native workers and labour migrants, 2 within and 1 between facilities. On-site inspections found adequate implementation of preventative measures to which both native workers and labour migrants showed suboptimal adherence. Being a labour migrant was associated with living in shared housing, but not with more contacts or different sources.

CONCLUSIONS

The fruit and vegetable packaging industry gave the impression of sufficient preparedness and control. Suboptimal adherence to the facilities' preventative guidelines could have facilitated work floor transmission. Community and household transmission are likely to have contributed to outbreaks. We encourage further research into risk factors for transmission in labour migrants and application of these insights into targeted public health policy.

Multiple relationships between aerosol and COVID-19: A framework for global studies

COVID-19 (Corona Virus Disease 2019) is a severe respiratory syndrome currently causing a human global pandemic. The original virus, along with newer variants, is highly transmissible. Aerosols are a multiphase system consisting of the atmosphere with suspended solid and liquid particles, which can carry toxic and harmful substances; especially the liquid components. The degree to which aerosols can carry the virus and cause COVID-19 disease is of significant research importance. In this study, we have discussed aerosol transmission as the pathway of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), and the aerosol pollution reduction as a consequence of the COVID-19 lockdown. The aerosol transmission routes of the SARS-CoV-2 can be further subdivided into proximal human-exhaled aerosol transmission and potentially more distal ambient aerosol transmission. The human-exhaled aerosol transmission is a direct dispersion of the SARS-CoV-2. The ambient aerosol transmission is an indirect dispersion of the SARS-CoV-2 in which the aerosol acts as a carrier to spread the virus. This indirect dispersion can also stimulate the up-regulation of the expression of SARS-CoV-2 receptor ACE-2 (Angiotensin Converting Enzyme 2) and protease TMPRSS2 (Transmembrane Serine Protease 2), thereby increasing the incidence and mortality of COVID-19. From the aerosol quality data around the World, it can be seen that often atmospheric pollution has significantly decreased due to factors such as the reduction of traffic, industry, cooking and coal-burning emissions during the COVID-19 lockdown. The airborne transmission potential of SARS-CoV-2, the infectivity of the virus in ambient aerosols, and the reduction of aerosol pollution levels due to the lockdowns are crucial research subjects.

Possible transmission of viruses from contaminated human feces and sewage: Implications for SARS-CoV-2

Humanity has experienced outbreaks by viruses such as severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1) in 2003, Eastern respiratory syndrome coronavirus (MERS-CoV) in 2012, Ebola virus in 2014 and nowadays SARS-CoV-2. While clinicians seek for a vaccine to reduce the epidemic outbreak, environmental engineers need to understand consequence of virus entity in sewage given the reported persistency of viruses in human feces and sewage environments for more than days. Herein, we discuss about concerns associated with virus occurrence in human feces and sewage, with attention to the possible SARS-CoV-2 transmission routes, based on the review of recent studies on SARS-CoV-2 as well as the previous pandemic events. Given the reported environmental stability of coronavirus, the feces- and sewage-derived transmission routes may be of importance to prevent unprecedented spread of coronavirus disease 2019 (COVID-19) particularly in developing countries. However, so far, limited number of studies detected infectious SARS-CoV-2 even in human feces, whereas a number of virus RNA copies were identified in both feces and sewage specimens. Therefore, uncertainty remains in the possibility of this transmission pathway, and further investigation is warranted in future studies, for example, by increasing the number of specimens, examining the effectiveness of methods for viral viability test, considering the patient medical history, and so forth.

Transmission routes for SARS-CoV-2 infection: review of evidence

There is no specific treatment for SARS-CoV-2, and all infection control strategies are based on breaking the transmission chain of virus. The high transmission rate of SARS-CoV-2 has raised many questions about the possible routes of infection transmission. Due to uncertainty of the main transmission routes, the infection control policies faced with more challenges. The possible main route of transmission is thought to be the close contact and respiratory droplets. Therefore, it is necessary to maintain physical distance and using the face mask. Another routes of transmission are through contaminated surfaces as well as airborne, fecal-oral transmission.

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Airborne transmission of SARS-COV-2 emphasizes the importance of using face masks in crowded and closed places.

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Household contact tracing of index COVID-19 cases can be applied as important part of COVID-19 control programs.

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Vertical transmission of SARS-COV-2 seems possible, but the risk is very low.

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SARS-COV-2 may transmit through oral intercourse, it is unlikely that this route will be a significant mean of transmission.

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Similarity of SARS-COV-2 with SARS, supports the hypothesis of non-transmission through blood.

COVID-19 virus may have neuroinvasive potential and cause neurological complications: a perspective review

Coronavirus disease 2019 (COVID-19) was reported at the end of 2019 in China for the first time and has rapidly spread throughout the world as a pandemic. Since COVID-19 causes mild to severe acute respiratory syndrome, most studies in this field have only focused on different aspects of pathogenesis in the respiratory system. However, evidence suggests that COVID-19 may affect the central nervous system (CNS). Given the outbreak of COVID-19, it seems necessary to perform investigations on the possible neurological complications in patients who suffered from COVID-19. Here, we reviewed the evidence of the neuroinvasive potential of coronaviruses and discussed the possible pathogenic processes in CNS infection by COVID-19 to provide a precise insight for future studies.

Managing emerging challenges of Coronavirus disease 2019 (COVID-19) in dentistry

Dental centers have been referred to as a hub or reservoir for infection, where healthcare professionals and other staff, patients and the public together may potentially spread pathogenic microorganisms. This may occur via saliva, skin or indirectly through air, water, and contaminated surfaces or instruments. Everyone should therefore be considered as potential sources of infection. During a pandemic, limiting unnecessary care has been adopted as a clinical measure for some patient's, to reduce the risk of cross-infection in the short term. However, in order to enable continuation of necessary and qualified care, dental processes need to follow specific infection control strategies in order to prevent transmission of emerging pandemic risks following COVID-19. In this article, we develop a tool with practical recommendations to mitigate infection risks before, during and following pandemics to enable ongoing dental care provision in primary and secondary care based on national and global recommendations.

Realigning the conventional routes of transmission: an improved model for occupational exposure assessment and infection prevention

Current recommendations for standard and transmission-based precautions in place for patients who are suspected or known to be infected or colonized with infectious agents are best suited to prevent the transfer of micro-organisms to other patients - that is, to prevent the acquisition of a healthcare-associated infection, rather than to protect the healthcare worker from self-contamination resulting in a potential occupationally acquired infection. This article reviews current recommended infection prevention and control practices and offers a framework for better protection and controls from an occupational health point of view. We offer a model with two exposure routes - contact and aerosol - resulting from work activities and environments, shifting the focus away from particular pathogenic micro-organisms' typical methods for spreading to patients or to other non-workers in hospital and community settings.

Awareness of HIV/AIDS and its routes of transmission as well as access to health knowledge among rural residents in Western China: a cross-sectional study

BACKGROUND

The purpose of this study was to evaluate the coverage of HIV health education among rural residents in western China by ascertaining their awareness of HIV/AIDS and its transmission routes, and to investigate how these residents receive health information.

METHODS

A survey was conducted through stratified clustered sampling at 99 county hospitals in 11 provinces in western China. Information was collected on awareness of HIV/AIDS and its transmission routes, as well as residents' access to health knowledge. Chi-square analysis was used to analyse the differences in HIV/AIDS awareness (knowing of the existence of HIV/AIDS, hereinafter referred to as "HIV awareness rate") between different subgroups categorized by demographic status, regional factors, and different methods of access to health knowledge. To further analyse the effects of access to health knowledge on HIV awareness, a logistic regression model was established. The relationship between access to health knowledge and transmission routes was also examined using chi-square analysis.

RESULTS

The HIV awareness rate of the total 9274 participants was 80.9%. There were statistically significant differences between subgroups classified by age (χ² = 482.118, p<0.001), education (χ² = 853.465, p<0.001), occupation (χ² = 340.553, p<0.001), income (χ² = 186.448, p<0.001), cumulative HIV cases according to province (χ² = 59.513, p<0.001), per capita annual net income of rural households according to province (χ² = 64.676, p<0.001), proportion of minority population according to province (χ² = 94.898, p<0.001), direct access to health knowledge (medical staff: χ² = 419.775, p<0.001; mass media: χ² = 740.238, p<0.001; family members: χ² = 12.189, p<0.001; socializing: χ² = 48.780, p<0.001; health education activities: χ² = 154.400, p<0.001), and indirect access to health knowledge (having a non-communicable disease with medical instructions χ² = 78.709, p<0.001; physical examinations: χ² = 135.679, p<0.001). The logistic regression model showed that education and mass media had the strongest impacts on HIV awareness among all methods of access. Participants had the least awareness of HIV's mother-to-child transmission route.

CONCLUSION

The HIV awareness rate indicated that previous HIV health education covered 80% of the rural population in western China. Mass media should take greater responsibility in HIV health education for the general population, and special attention should be paid to the elderly, the most impoverished population, minority community as well as the mother-to-child transmission route.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.

Prevalence and distribution of hepatitis C virus genotypes in Galicia during the period 2000-2015

INTRODUCTION

We present the largest study conducted in Galicia on the prevalence and distribution of HCV genotypes/subtypes.

METHODS

Retrospective study collecting the total number of patients chronically infected by HCV between 2000.01.01 to 2015.12.31 in 3of the main health areas: Santiago, Pontevedra and Vigo.

RESULTS

We collected a total of 4469 patients. The median age was 50 years (IQR 57-45), 72,3% were men, 0,4% were coinfected with another genotype, 20,6% were coinfected with HIV and 35.2% with HBV. The main route of transmission was parenteral (83,1%), followed by unknown (15,3%), sexual (1,4%) and vertical (0,2%). The distribution of genotypes was: 62,9% HCV-1 (29,2% HCV-1a and 31,9% HCV-1b), 3,4% HCV-2, 21,0% HCV-3, 12,6% HCV-4 and 0,1% HCV-5.

CONCLUSION

The distribution of genotypes in Galicia shows significant differences with respect to that observed in Spain. This distribution varies with age, gender, coinfection with HIV and/or HBV, and within geographical areas.

Neurological manifestations of Zika virus infection

Zika virus (ZIKV) is a flavivirus (Flaviviridae family) transmitted mainly by Aedes mosquitoes. The virus was restricted to the African continent until its spread to south-east Asia in the 1980's, the Micronesia in 2007, the French Polynesia in 2013 and, more recently in the Americas in 2015, where, up to date, the World Health Organization (WHO) has estimated about 3-4 million total cases of ZIKV infection. During outbreaks in the French Polynesia and Brazil in 2013 and 2015, respectively, national health authorities reported potential neurological complications of ZIKV disease, chiefly an upsurge in Guillain-Barré syndrome, which coincided with ZIKV outbreaks. On the other hand, the emergence of ZIKV in Brazil has been associated with a striking increase in the number of reported cases of microcephaly in fetus and newborns, twenty times higher than in that reported in previous years. While investigations are currently assessing whether there is an actual association between neurological complications and ZIKV infections, the evidence was enough worrisome for WHO to declare a public health emergency of international concern. Here we present an updated review addressing what is currently known about the possible association between ZIKV infection and the development of severe neurological disorders.

Targeting Transmission Pathways for Emerging Zoonotic Disease Surveillance and Control

We used literature searches and a database of all reported emerging infectious diseases (EIDs) to analyze the most important transmission pathways (e.g., vector-borne, aerosol droplet transmitted) for emerging zoonoses. Our results suggest that at the broad scale, the likelihood of transmission occurring through any one pathway is approximately equal. However, the major transmission pathways for zoonoses differ widely according to the specific underlying drivers of EID events (e.g., land-use change, agricultural intensification). These results can be used to develop better targeting of surveillance for, and more effective control of newly emerged zoonoses in regions under different underlying pressures that drive disease emergence.

Bacterial endosymbionts in field-collected samples of Trialeurodes sp. nr. abutiloneus (Hemiptera: Aleyrodidae)

Facultative bacterial endosymbionts are common, influential associates of arthropods, yet their movement among host species has not been well documented. Plant-mediated transmission of Rickettsia has been shown for the whitefly Bemisia tabaci. Bemisia tabaci in USA cotton fields harbors the secondary symbionts Rickettsia and Hamiltonella, and co-occurs with Trialeurodes sp. nr. abutiloneus whiteflies. To determine whether symbionts may be shared, the microbial diversity of these whiteflies on cotton across the USA was analyzed. Trialeurodes sp. nr. abutiloneus bore Portiera, Pseudomonas, Serratia, Arsenophonus and Wolbachia. No Rickettsia or Hamiltonella were detected. These results provide no evidence for horizontal transmission of symbionts between these whitefly genera.